This project concerns characterization of the surface components of a recently defined veterinary pathogen: the causative agent of contagious equine metritis (CEM). CEM is a sexually transmitted venereal disease of horses; the etiological agent is an unclassified gram-negative diplococcus which shares several morphological and biochemical characteristics with Neisseria gonorrhoeae. In addition, the disease profile of CEM bears some resemblance to gonorrhea in humans. Studies have focused on the (1) formulation of a clear-typing medium which provides for adequate growth and subsequent, (2) evaluation of colony morphology on this medium, (3) evaluation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the constituents of the whole cell lysates as well as surface iodinated components, and (4) preliminary evaluation of the molecular nature of lipopolysaccharide as determined by SDS-PAGE of proteinase-K digested whole cell lysates.